Download Fetal CHF

Fetal Congestive Heart Failure
Shabib Alhadheri, MD
Fetal Anatomy & Physiology
• Brain and heart get highest oxygenated blood
(from UV)
• Lower body gets less oxygenated blood (from
RV)
• Pulmonary = systemic pressure
• Lowest flow at aortic isthmus
• Both lungs receive only 10% of CO and have the
highest vascular resistance
• Since the blood is oxygenated in the placenta,
the O2 sat in the IVC (70%) is higher than that
in the SVC (40%)
• The highest pO2 is found in the umbilical vein
(32 mmHg)
Fetal Circulation
• Parallel circulations
• Mixing of venous returns
• High resistance of the
pulmonary circulation
• Low resistance of the
placental circulation
• Presence of shunts
• Right ventricular
dominance
• Non-compliant behavior of
ventricular filling in utero
• Limited range of HR over
which CO can be
maintained
Fetal Circulation
Fetal Myocardium
• Fetal myocardial fibers generate less
active tension when compared to adults
• Resting tension is higher in fetal cells
• Higher proportion of non-contractile
proteins in fetal cells
Fetal Myocardium
• The RV is the dominant ventricle
ejecting the combined CO into the
descending aorta
• The LV supplies a more highly saturated
yet smaller proportion of combined CO
to coronaries, head, brain and forelimbs
• The fetal ventricles are limited in their
ability to increase stroke volume in
response to increased HR
Fetal Hemodynamics
• Fewer contractile elements affects
diastolic performance
• Atrioventricular valve E:A ratio
– < 1 in utero
– ~ 1 near term
– > 1 postnatally
• Maturation improves ventricular
relaxation
Foramen Ovale Restriction
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Progressive right atrial enlargement
RV dilation and hypertrophy,
MPA/DA enlargement
Reduced growth of the left heart
PDA Constriction
• May occur naturally but more commonly seen
in maternal prostaglandin inhibitors ingestion
• Results in RV pressure overload, hydrops
fetalis
• On Echo:
– elevated peak systolic flow velocities across
DA (> 1m/s); associated high diastolic flow
velocity
– Associated with TR; increased MPA pressure
• Severity related to amount of elevated diastolic
velocity of the pulmonary artery
Transitional Circulation
• Cord is clamped, baby cries
– Systemic vascular resistance (SVR) jumps
– LV end diastolic pressure (LVEDP) increases
– Lungs expand
– Pulmonary capillaries see high pO2
– Pulmonary vascular resistance (PVR) falls
– Ductus arteriosus constricts
Causes of Fetal CHF
Fetal tachy/bradyarrhythmias
Anemia/hemoglobinopathy
Fetal systemic infection/myocarditis (parvovirus)
Congenital heart disease with valvular
regurgitation
• Non-cardiac malformations e.g. diaphragmatic
hernia or cystic hygroma
• Twin-twin transfusion recipient volume and
pressure overload
• Atrioventricular fistula with high cardiac output
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What You Need To Know?
Fetal heart rate
Cardiomegaly
Myocardial function
Pulsed Doppler evaluation of the IVC
Pulsed Doppler of the umbilical cord
Color and pulsed Doppler of the cardiac
valves
• Evidence for hydrops fetalis
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Fetal Heart Rate
• Bradycardia
– Mechanical PR interval
– Complete heart block
• Tachycardia
– SVT
– Atrial flutter
HR… M-Mode
HR… Doppler Study
Supraventricular Tachycardia (SVT)
Atrial Flutter
Complete Heart Block
Cardiomegaly
• The most common
cardiac chamber to
show enlargement is
the right atrium
• C/T area ratio = cardiac
area/chest area (normal
0.25-0.35)
• C/T circumference ratio
= cardiac circ/chest circ
(normal <0.5)
Myocardial function
• Decreased fractional shortening
• Valvular regurgitation
Myocardial Performance Index (MPI)
(Tei Index)
• Using the filling time of AV valve and ejection time of
the ventricle
Normal values at 18-31
weeks gestation
-TI
0.53+/- 0.13
-ICT 43+/- 14ms
-IRT 48+/- 13ms
-ET 173+/- 16 ms
Friedman et al; Ultrasound in Obst & Gyn, Vol 21 issue 1, 33-36, Jan 2003
Myocardial Performance Index (MPI)
• A ventricular geometry-independent
measure of combined systolic and
diastolic ventricular performance
• Obtained by Doppler sampling of inflow
and outflow across the ventricle
measuring the time intervals relating to
isovolumic contraction (ICT), isovolumic
relaxation (IRT), and ventricular
ejection (ET)
Tricuspid Regurgitation
• The true BP and ventricular cavity pressure in
the human fetus is unknown
• The typical peak systolic pressure for a
newborn premature infant born at 24 weeks’
gestation is ~ 30-40 mmHg
• The normal fetal heart in series with the low
placental vascular resistance, the fetal
pressure should be less
• Therefore, elevated RVp reflects increased
vascular resistance
Pulsatility Index
• A Doppler-derived measure of placental
vascular resistance (PVR)
• Obtained by Doppler interrogation of the
umbilical artery
• Calculated as maximum systolic – end-diastolic
velocity/ mean velocity (normal mean 2.46 +/0.52)
• When there is a low, absent, or even reversed
diastolic flow velocity at end-diastole, this
suggests a very high PVR
Abnormal Doppler Pattern
• As the ventricles become more stiff
(less compliant), the Doppler
parameters of ventricular filling begin to
change
• The normal double-peak inflow pattern
(passive filling “E wave” and active
atrial filling “A wave”) fuse into a singlepeak
Abnormal Venous Doppler
• Reversal away from the heart during atrial
contraction is a sign of increased end-diastolic
pressure in the ventricles of the failing heart
• Increased atrial reversal in the inferior vena
cava
• Ductus venosus atrial reversal
• Umbilical venous atrial pulsations (diastolic
block… predicts perinatal mortality)
Abnormal Doppler Pattern
• Ductus venosus flow during atrial
contraction diminishes, often becoming
absent or reversed in case of a very
stiff, noncompliant right ventricle
• Pulsations in the umbilical vein reflects
a severe degree of impediment to
ventricular filling (diastolic dysfunction)
Inferior Vena Cava Flow
Normal fetus with a
small amount of flow
reversal
A fetus with poor RV
compliance showing
an increased degree of
flow reversal
Ductus Venosus Flow
Normal flow pattern
with continuous
forward flow
Some reversal flow
(arrows), suggesting a
stiff abnormal heart
Umbilical Cord Doppler
Normal pattern
- Pulsatile umbilical artery flow
- Continuous venous flow
UA
UV
Decreased diastolic velocity with
reversal flow (arrows) with
pulsatile venous flow, suggestive
of elevated placental vascular
resistance
Inflow Patterns
Fetal
Post-Natal
Inflow Pattern
Double-peak
Single-peak
TV
Hydrops Fetalis
• Imbalance between supply and demand
• Development of abnormal fluid collection
in the fetus, in more than one site
– Abdomen (ascites)
– Pleural or pericardial space (effusion)
– Skin (subcutaneous edema “>5mm
thickness”)
Non-Immune Hydrops Fetalis… Causes
Etiology / Pathogenesis:
Percent
Cardiovascular
( NIHF via CHF)
Chromosomal abnormalities
17 – 35 %
14 – 16 %
(e.g. Turner, Noonan syndromes)
4 – 12 %
Hematologic
(NIHF 20 severe fetal anemia leading
to high output cardiac failure)
Norton et al., 1994
Fetal Hydrops-Pleural/Pericardial Effusions
Fetal Hydrops-Ascites
Fetal Hydrops-IVC flow reversal
Fetal Hydrops-UV pulsations
Summary
• Redistribution of cardiac output
– Absent end diastolic flow in umbilical artery with brain sparing
• Cardiomegaly
• Abnormal venous Doppler
– Flow reversal in IVC
– Umbilical venous pulsations
• Abnormal myocardial function
– Decreased shortening fraction
– Valvular regurgitation
James Huhta, Seminars in Fetal & Neonatal Medicine (2005) 10, 542-552
Thank You